Episode 6: jQuery Accordion

jQuery Accordion

In this video, we’ll walk through creating a simple content accordion. All of the sample content for the demo comes from Wikipedia.

Since we’ll be using a lot of special characters, we have to pay special attention to our charset meta tag to make sure all those special characters show up as expected rather than looking look a bunch of gobbledygook.

There are lots of different bits of HTML markup that can be used to create the HTML markup for an accordion, but I like to use a definition list (<dl>). I use the <dt> tags for the accordion titles and the <dd> tags for the accordion content areas. The <dd> tag can contain any other tags so the content can be quite complex, including headings, paragraphs, lists, images, videos, etc.

In this case, I’m making use of the new HTML <figure> and <figcaption> elements for presenting the photos and captions for each city. For the image captions, I’m using the captions provided by Wikipedia to ensure that the photographers are correctly credited for the use of their images.

Once we’ve got all of our content on the page, we’ll style that up with a bit of CSS to make it look like an accordion. After removing some of the browser’s default styles, we add a background color and some rounded corners to the titles and a border around the content areas.

Now we can see the page the way our site visitors who don’t have JavaScript enabled will see. The page looks nice, and these site visitors will never know they’re missing out on anything at all.

With the HTML and CSS out of the way, we can jump into the JavaScript. First up, we hide all of the <dd> tags to fold them out of the way. Then, we add a click handler to the <dt> tags that moves to the next <dd> tag and shows it when the <dt> is clicked.

That’s a bit of progress, but we have to add a bit more finesse to get it working like an accordion, like closing any other open panels when we click to open a new one. We make use some of the DOM traversal methods we used last time – next() and siblings(). We also make use of some of jQuery’s built-in animations – slideUp(), slideDown(), and slideToggle() – which we’ll be covering in detail in next week’s video.

Now that the basic accordion is working, we’ll apply some snazzy CSS and JavaScript techniques to write some special additional styles for the accordion to make it extra special and polished. We take a look at the famous body-class switching trick to write separate CSS styles depending on whether or not JavaScript is enabled. Using the body class, we write some extra CSS to make the <dt>‘s look and work a little more like buttons, and we add a class to the <dt> when they’re open so that the open panel can be styled a bit differently from the panels that are closed.

Pro Tip: Rather than adding color changes, sizes, borders and other CSS changes in your JavaScript, put style changes in your CSS file instead, and then just use JavaScript to add and remove CSS class names to control changes in style.

We’ll wrap up by making a few little optimizations – we toggle the ‘+’ and ‘-‘ characters to show if the panel is opened or closed, and style the <dd> content areas to match the orange color of the open titles. And we learn how to use a CSS3 transition to animate a background color change.

Creating a simple accordion is pretty simple – most of the work is in the CSS, and we use just a few lines of JavaScript to make it all work.

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